Method for estimating an operating state of an optical interferometry system, corresponding computer program and device

Abstract

This method is designed to estimate an operating state of an interferometry system (10) comprising an optical interferometer (14), for providing two separate optical signals (s1, s2) from the same periodic optical signal (s0) of period T, combined with a multimodal coupler (24) capable of providing a multiphase system of N≥2 optical signals (s'1, s'2, s'3) formed to be phase-shifted from each other. It comprises a calculation of at least one characteristic operating value (SC, DC1, DC2, DC3, DO1, DO2, DO3) defined from at least one measurement (S) of the multiphase system. Depending on this at least one characteristic operating value and at least one predefined reference value, it comprises the determination of an operating state (E0, E1, E2, E3) of the interaction branch (20) of the optical interferometer (14) and / or of at least one of the N outputs of the multimodal coupler (24). Figure for the abstract: Fig. 1

Description

Title of the invention: Method for estimating an operating state of an optical interferometry system, corresponding computer program and device

[0001] The present invention relates to a method for estimating an operating state of an optical interferometry system. It also relates to a corresponding computer program and device.

[0002] An industrial application particularly targeted by the present invention, but not exclusively, concerns the characterization of fluid, liquid or gas, by optical interferometry. But other industrial applications are conceivable.

[0003] An electronic device for characterizing a fluid, liquid or gaseous, by optical interferometry comprises at least one sensor designed to interact with the fluid, generally referred to as an “olfactory sensor” and a transducer processing, by optical interferometry, the signals resulting from this interaction to provide a sequence of at least one measurement signal representative of an interaction of the fluid with each sensor. It generally comprises as many optical interferometry systems as there are sensors.

[0004] It is understood that the interaction with the fluid, the provision of the sequence of measurement signals and its possible processing are operations which can be carried out in parallel over time. Alternatively, the processing can be carried out a posteriori.

[0005] This type of device is sometimes called a multivariate sensor, particularly when it comprises a plurality of sensors. It can be considered for various olfactory estimation applications and is generally, in this case, referred to as an “electronic nose” (in a gaseous medium) or “electronic tongue” (in a liquid medium). It is then used to detect, discriminate, identify and quantify volatile organic compounds in a gaseous fluid to be analyzed, or compounds present in a liquid. It can be used in various industrial fields such as: the perfume industry, for example to compare, study or design pure or mixed olfactory compositions, environmental protection, in particular to detect odorous pollution or monitor the quality of more or less confined environments, monitoring of industrial sites presenting a risk of contamination by volatile materials or materials soluble in a potentially dangerous solvent or odorous, - health, for example to offer a smell substitute to people suffering from anosmia or to detect volatile biological markers such as the emanations of infectious microbiological activity, - the food industry, for example to detect contamination in a food manufacturing and / or distribution chain, - any other industrial field in which the control of any odorous product may prove useful.

[0006] The invention applies more particularly to the estimation of an operating state of an interferometry system comprising an optical interferometer with a reference branch and an interaction branch, for the supply of two separate optical signals originating from the same periodic optical signal (s0) of period T, combined with a multimodal coupler with N>2 outputs, capable of supplying a multiphase system of N optical signals formed to be phase-shifted from each other in the period T from the two separate optical signals.

[0007] Such an interferometry system is particularly advantageous for an electronic fluid characterization device, further provided with a unit for processing the multiphase system to extract therefrom an estimate of the phase shift between the two optical signals supplied by the optical interferometer, because it makes it possible to determine without any ambiguity modulo T the evolution over time of the phase shift, generally in the form of a time signal called a "sensorgram" characteristic of the interaction of the fluid with any suitable sensor, between the two optical signals.The operating principle of an electronic device for characterizing a fluid, comprising 64 different olfactory sensors and 64 associated interferometric systems as defined previously for the provision of 64 sen-sorgrams, is for example described in the article by Laplatine et al, entitled “Silicon photonic olfactory sensor based on an array of 64 biofunctionalized Mach-Zehnder in-terferometers”, published in Optics Express, volume 30, no. 19, dated September 12, 2022.

[0008] But an interferometric system according to the present invention is more generally applicable to any detection device producing two optical signals, originating from the same periodic signal of period T processed by interferometry, of which it is desired to determine the phase shift at any instant without ambiguity modulo T. In general the periodic signal is of sinusoidal form and of period expressed angularly, hence a period T generally equal to 2ir.

[0009] During its use, this type of interferometry system is likely to see its operation deteriorate, in particular due to possible deterioration of the interaction branch of the optical interferometer or the outputs of the multimodal coupler. These elements, in direct contact with the environment in which it is placed the system, are fragile and subject to the impact of pollution, dust, possible micro-droplets of liquid, or any other external agent. They are also susceptible to internal malfunctions.

[0010] In the worst case, the damage is not detected and neither is the malfunction of the interferometric system. This results in distorted and increasingly unreliable measurements.

[0011] In the event of detection of suspicious behavior, a visual inspection of the interaction branch of the optical interferometer or the outputs of the multimodal coupler of the interferometry system can be carried out. But when many interferometry systems are mounted on a chip, for integration into the same detection device such as that of the aforementioned article by Laplatine et al for example, the latter must then be dismantled before being inspected. Visual inspection is already tedious in itself. It is also risky since the risk of additional pollution is high. Furthermore, in the case of an electronic fluid characterization device, this operation requires the removal of the interaction branches of the interferometry systems from the chip of a fluid cavity. The risk of damage during disassembly is therefore also high.

[0012] In the case of an electronic fluid characterization device also, the provided sensorgrams can be analyzed a posteriori without dismantling the chip. Those that are individually detected as faulty can be ignored, which amounts to ignoring the corresponding olfactory sensors. But this is in reality only visible on sensorgrams that are already very degraded.

[0013] Finally, in all cases, no existing method provides for anticipating the malfunction and the remaining lifetime of an interferometry system such as the aforementioned.

[0014] It may thus be desired to provide a method for estimating an operating state of an interferometry system of the aforementioned type, i.e. a combination of optical interferometer and multimodal coupler, which makes it possible to overcome at least some of the aforementioned problems and constraints.

[0015] A method is therefore proposed for estimating an operating state of an interferometry system comprising an optical interferometer with a reference branch and an interaction branch, for providing two separate optical signals from the same periodic optical signal of period T, combined with a multimodal coupler with N>2 outputs, capable of providing a multiphase system of N optical signals formed to be phase-shifted from each other in the period T from the two separate optical signals, comprising: - a calculation of at least one characteristic operating value defined from at least one measurement of the multiphase system; and - based on this at least one characteristic operating value and of at least one predefined reference value, the determination of an operating state of the interaction branch of the optical interferometer and / or of at least one of the N outputs of the multimodal coupler.

[0016] Thus, by planning to calculate at least one characteristic operating value directly from a measurement of the multiphase system provided by the interferometry system, whatever it may be, rather than mechanically extracting the interferometry system from the device in which it is implanted or relying on possible resulting sensorgrams, it becomes easier to anticipate and identify a malfunction of the interaction branch of the optical interferometer and / or of at least one of the N outputs of the multimodal coupler and to follow its evolution. This proposal is in itself both simple and clever. It is then within the reach of those skilled in the art to identify what characteristics may be to be extracted from the multiphase system so that they are indicative of this or that defect.

[0017] Optionally, a method for estimating an operating state of an interferometry system according to the invention may further comprise an estimation of the remaining lifetime of the interferometry system as a function of a change over time of at least one of said at least one characteristic operating value.

[0018] Also optionally, the calculation of said at least one characteristic operating value comprises: - the calculation of at least one static value defined from values ​​taken by said at least one measurement of the multiphase system at a predetermined instant; and - the calculation of at least one dynamic value defined from values ​​taken by said at least one measurement of the multiphase system during a predetermined duration subject to a condition of sufficient variation of the optical signals of the multiphase system, this calculation being carried out only if this condition of sufficient variation is actually fulfilled.

[0019] Also optionally, the sufficient variation condition includes the fact that each optical signal of the multiphase system results from enough different phase shift values ​​so that they cover at least the period T.

[0020] Also optionally, said at least one characteristic operating value comprises a static contrast SC value defined from extreme values ​​taken by said at least one measurement of the multiphase system at a predetermined instant, for example: - at an instant Îq where the interaction branch of the optical interferometer is exposed to a reference environment; and max(p.(t0) )-rnin(p.(tü) ) , where p (t0) is the measure of the amplitude of the i-max ( P, ( tü ) ) +min ( p ( t0 ) ) th optical signal of the multiphase system at time t{) or the measurement of an average of the amplitude of the i-th optical signal of the multiphase system around time tg.

[0021] Also optionally: - at least one reference static contrast value is predefined, in particular by learning on several reference interferometry systems whose operating states of interaction branches are known; - the static contrast SC value is compared to this at least one reference static contrast value to determine whether the interaction branch of the optical interferometer is in good working order or not.

[0022] Also optionally, said at least one characteristic operating value comprises a dynamic contrast value DQ defined for each i-th optical signal of the multiphase system from extreme values ​​taken by said at least one measurement of this i-th optical signal of the multiphase system during a predetermined duration D, for example: - for a duration D, where the interaction branch of the optical interferometer is exposed to an unstable interaction environment, subject to a condition of sufficient variation of the optical signals of the multiphase system ; And , where k is a kx max . teD -min teD - according to the definition pQ proportionality factor, for example 0.5, and p(t) is the measure of the amplitude of the i-th optical signal of the multiphase system at time 1.

[0023] Also optionally, said at least one characteristic operating value comprises a dynamic offset value DC^ defined for each i-th optical signal of the multiphase system from extreme values ​​taken by said at least one measurement of this i-th optical signal of the multiphase system during a predetermined duration D, for example: - for a duration D, where the interaction branch of the optical interferometer is exposed to an unstable interaction environment, subject to a condition of sufficient variation of the optical signals of the multiphase system ; And according to the definition Dq - kx [ max ( p. ( t ) ) 4- min ( p. ( t ) ) 1 L êD ' i 7 -1 teD D 7 ' where k is a proportionality factor, for example 0.5, and p,(t) is the measure of the amplitude of the i-th optical signal of the multiphase system at time t.

[0024] A method is also proposed for estimating an operating state of an installation with a shared plurality of interferometry systems, each comprising an optical interferometer with a reference branch and an interaction branch, for providing two separate optical signals from the same periodic optical signal of period T, combined with a multimodal coupler with N>2 outputs, capable of providing a multiphase system of N optical signals formed to be phase-shifted from each other in the period T from the two separate optical signals, this installation being in particular intended to be integrated into an electronic fluid characterization device, the method comprising the execution of the steps of a method according to the invention for each of its interferometry systems so as to extrapolate the determination of an overall operating state of the installation.

[0025] There is also provided a computer program downloadable from a communication network and / or recorded on a computer-readable medium and / or executable by a processor, comprising instructions for executing the steps of a method for estimating an operating state of an interferometry system according to the invention or of an installation with a shared plurality of interferometry systems according to the invention, when said program is executed on a computer.

[0026] A device is also proposed for estimating an operating state of at least one interferometry system, each interferometry system comprising an optical interferometer with a reference branch and an interaction branch, for providing two separate optical signals from the same periodic optical signal (s0) of period T, combined with a multimodal coupler with N>2 outputs, capable of providing a multiphase system (S) of N optical signals formed to be phase-shifted from each other in the period T from the two separate optical signals, the estimation device comprising: - an optical sensor of the N outputs of each multimodal coupler to obtain measurement signals from each multiphase system; - a measurement signal processing unit;

[0027] wherein the measurement signal processing unit is configured to: - extract at least one measurement of each multiphase system from the measurement signals and calculate at least one defined operating characteristic value from this at least one measurement; and - based on this at least one characteristic operating value and at least one predefined reference value, determine an operating state of the interaction branch of the optical interferometer and / or at least one of the N outputs of the multimodal coupler of each system of interferometry.

[0028] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: - [Fig.l] schematically represents the general structure of a system interferometry and a device for estimating its operating state according to an embodiment of the invention, such that they can be integrated into a phase shift estimation device, - [Fig.2] illustrates, using a representative time diagram of a measurement of a multiphase system which can be provided at the output of the interferometry system of [Fig.l], different values ​​used by the estimation device of [Fig.l] to provide an estimate of its operating state, - [Fig.3] illustrates an example of relevance and interpretation of a first operating characteristic that can be calculated by the estimation device of [Fig.l], - [Fig.4] illustrates an example of relevance and interpretation of a second operating characteristic that can be calculated by the estimation device of [Fig.l], - [Fig.5] schematically represents the general structure of a plurality of interferometry systems and a shared device for estimating their operating status, such that they can be integrated into a phase shift estimation device, - [Fig.6] illustrates the successive stages of a process for estimating a state of operation of an interferometry system, according to one embodiment of the invention, - [Fig.7] schematically represents the general structure of a device electronic characterization of a fluid capable of implementing the process of [Fig.6], - [Fig.8A] illustrates an example of a time diagram in which provide several response signals, or sensorgrams, which can be obtained by the electronic device of [Fig.7], under controlled multivariate measurement conditions, - [Fig.8B] illustrates, in the form of a circular diagram, an example of a standardized signature that can be calculated by the electronic device of [Fig.7] from sensorgrams such as those of [Fig.8A], and - [Fig.9] illustrates the successive stages of a process for characterizing a fluid which can be implemented by the electronic device of [Fig.7].

[0029] The installation shown schematically in [Fig.l] comprises a system interferometry 10 and a device 12 for estimating its operating state.

[0030] The interferometry system 10 comprises an optical interferometer 14, for example a Mach-Zehnder optical interferometer. Such an optical interferometer 14 receives a single periodic coherent optical signal s0 of period T, in particular a sinusoidal optical signal s0 of pulsation 2irf where f is the carrier frequency, generated and emitted, in a waveguide, for example by a laser source 16 of coherent light. The period T can be defined temporally, in which case it is the inverse of the carrier frequency, or angularly, in which case it is 2ir for a sinusoidal signal.

[0031] In the optical interferometer 14, the periodic signal s0 is conducted to two distinct optical branches generally of the same length, one constituting a reference optical branch 18, the other an interaction optical branch 20. The first, the reference optical branch 18, produces a first periodic optical signal Si whose phase shift with respect to s0 depends on the length traveled in this reference optical branch 18. The second, the interaction optical branch 20, produces a second periodic optical signal s2 whose phase shift with respect to s0 depends not only on the same length traveled in this interaction optical branch 20, but also on an optical interaction with an interaction device 22 arranged on this path. The possible phase shift between Si and s2 therefore depends directly on the optical interaction with the device 22.

[0032] For a fluid, liquid or gaseous characterization application, the interaction device 22 is a sensor designed to interact with the fluid, including in particular a reactive site onto which are grafted reactive components capable of interacting by adsorption / desorption with compounds likely to be present in the fluid. By these interactions, the refractive index in the optical interaction branch 20 is locally modifiable and variable over time, which generates the aforementioned phase shift between Si and s2, as well as its variation over time which produces a temporal phase shift signal generally called a sensorgram.

[0033] Other applications are conceivable and any interaction device 22 capable of having an impact on the phase shift of the signal s2 is suitable. More generally, depending on the applications, other interferometric systems may be suitable, other than a Mach-Zehnder optical interferometer. It is for example possible to provide a Fizeau, Fabry-Pérot, Jamin, Ramsey-Bordé, Michelson, etc. interferometer, or even a combination of optical interferometers.

[0034] At the output of the optical interferometer 14, the two periodic optical signals Si and s 2 could be recombined to interfere with each other and produce a single baseband signal carrying the phase shift information. But the latter is then ambiguous, so that they are advantageously provided as input signals of a multimodal coupler 24 with two inputs for receiving the two separate periodic optical signals Si and s2, and with N outputs, N > 2, for providing a multiphase system of N baseband signals formed to be phase-shifted from each other in the period T, for example by T / N when it is desired to impose a regular phase shift. In the case of sinusoidal optical signals, the period T of which can be defined angularly at 2ir as indicated previously, and for a multimodal coupler with three outputs such as that illustrated as a simple non-limiting example in [Fig.l], a three-phase system of three sinusoidal optical signals s'i, s'2 and s'3 phase-shifted from each other by 2ir / 3 is provided. It will be noted, however, that any irregular phase shift can also be defined as a variant. But in the rest of the description, it is a regular phase shift of T / N which will be retained for the sake of simplicity.

[0035] In accordance with the general principles of the present invention, the device 12 for estimating an operating state of the interferometry system 10 is designed to extract at least one measurement of the multiphase system s'i, s'2, s'3 and to deduce therefrom by calculation at least one characteristic operating value.

[0036] For this purpose, the phase shift estimation device 12 comprises an optical sensor 26 associated with the outputs of the multimodal coupler 24. This is for example a camera provided with photoreceptors, such as a camera taking the form of a CCD (Charge Coupled Device) photographic sensor, for the supply, in the case of the supply by the multimodal coupler 24 of a three-phase optical system, of a three-phase electrical system S of three sinusoidal measurement signals pb p2 and p3 phase-shifted from each other by 2ir / 3. These three electrical signals take the following form: Pj(t) = a]Cos[0(t)] +O], ; p2(t) =a2cos[0(t)+2ît / 3]+o2 ; p3(t) = a3cos[0(t)-2tt / 3]+o3.

[0037] In this three-phase system of measurement signals S, aB a2 and a3 are values ​​of constant but a priori different amplitudes, which illustrates the fact that the three signals pb p2 and p3 are of different amplitudes due to imperfections in the laser source 16, the optical interferometer 14, the multimodal coupler 24 and / or the CCD sensor 26. Similarly, ob o2 and o3 are values ​​of constant but a priori different amplitude shifts, which illustrates the fact that the three signals pb p2 and p3 are of different amplitude shifts due to imperfections in the laser source 16, the optical interferometer 14, the multimodal coupler 24 and / or the CCD sensor 26. As for 0(t), this is the phase shift time signal to be estimated which is coded as if it were the common frequency of the three signals pb p2 and p3 of the three-phase measuring signal system S.

[0038] The three-phase system of measurement signals S is supplied at the input of a system in computer system 28 of the operating state estimation device 12, this computer system 28 being specifically configured for processing the three-phase system of measurement signals S in order to extract therefrom by calculation at least one characteristic operating value and, as a function of this at least one characteristic operating value and at least one predefined reference value, to determine an operating state of the interaction branch 20 of the optical interferometer 14 and / or at least one of the outputs of the multimodal coupler 24. Optionally, it can further be designed to estimate a remaining lifetime of the interferometry system 10 as a function of a change over time of at least one of the calculated characteristic operating value(s).

[0039] Also optionally, the computer system 28 of the device 12 for estimating an operating state of the interferometry system 10 can further be designed to estimate the phase shift between the two input signals S1 and S2 by processing the three-phase system of measurement signals S, as well as its evolution over time, in the form of a time signal SG of the sensorgram type, for example in the context of fluid characterization.

[0040] The computer system 28 as shown schematically in [Fig.l], comprises a processing unit 30 (i.e. a processor) conventionally associated with a memory 32 (for example a RAM memory or other, or a combination of memories of different known types).

[0041] This system can for example be implemented in a computer device such as a conventional computer comprising a processor associated with one or more memories for storing data files and computer programs whose instructions are intended to be executed by the processor. Their functions could also be at least partly microprogrammed or microwired in dedicated integrated circuits. Thus, as a variant, the computer device implementing the computer system 28 could be replaced by an electronic device composed solely of digital circuits (without a computer program) for carrying out the same actions. Also as a variant, at least part of the aforementioned computer programs could be remote and accessible by the computer system 28 via the Internet.Generally speaking, even if all the aforementioned software and memory components are presented as being gathered in the same computer system 28, they could just as well be dispersed in separate hardware elements, even distant from each other, but interconnected in a network (data transmission bus, local network, wide area network, Internet, etc.).

[0042] The computer system 28 is thus designed to process the three-phase system of measurement signals S, this processing being defined and configured in the form, for example, of instructions of a software module or computer program 34 recorded in memory 32 and executable by processing unit 30.

[0043] According to these instructions, the calculation of the characteristic operating value(s) comprises for example: - the calculation of at least one static value defined from values ​​taken by the three-phase system of measuring signals S at a predetermined instant, and - the calculation of at least one dynamic value defined from values ​​taken by the three-phase system of measuring signals S during a predetermined duration.

[0044] In the case of the calculation of a dynamic value, the duration may be subject to a condition of sufficient variation of the optical signals s'i, s'2, s'3 of the three-phase system, in the sense that the calculation is only carried out if the condition of sufficient variation is actually fulfilled during this duration.

[0045] It is within the reach of a person skilled in the art to design an implementation of the verification of this sufficient variation condition. But according to an advantageous and clever embodiment, it can include the fact that each signal of the three-phase system provided results from enough different phase shift values, for example according to a predefined model of distance between them and / or partitioning, so that they cover at least the period T, that is to say the period 2ir in the case of sinusoidal signals.It is then possible to reconstruct, at least by interpolation and for each signal of the three-phase system, a single sinusoidal signal passing as close as possible to this signal over at least one angular period covered, so that it becomes possible to deduce in particular its extreme values, therefore the values ​​of its amplitude and its amplitude shift, which makes it possible to deduce the parameters ai, a2, a3, ob o2 and o3 of the three-phase system of measurement signals S. .

[0046] Alternatively, the required sufficient variation condition may include the fact that each signal of the three-phase system provided varies sufficiently rapidly in amplitude to deduce its achievable extreme values. In other words, this means that it includes a sinusoidal-shaped time portion over at least one angular period allowing, at least by sinusoidal interpolation also, to estimate its extreme values. Thus, if at least sinusoidal interpolation is possible, then the estimation of the extreme values ​​from which the amplitude and the amplitude shift of each signal of the multi-phase system provided can be estimated is considered possible.

[0047] When the computer system 28 is further designed to estimate the phase shift between the two input signals S1 and S2 by processing the three-phase system of measurement signals S, this same condition can be applied, to only carry out a calibration prior to the phase shift if it is verified. It is for example applied directly if the calibration is carried out according to the teaching of the document of patent WO 2022 / 238170 A1, i.e. by applying a pre-calibration directly to the three-phase system of measuring signals S.

[0048] Alternatively, the required sufficient variation condition can be applied indirectly, i.e. on the supposed possibility of carrying out a reliable elliptical adjustment making it possible to obtain such an ellipse by Clarke transformation or equivalent of the three-phase system of measurement signals S, if a calibration is then carried out according to the teaching of the article by Halir et al, entitled “Direct and sensitive phase readout for integrated waveguide sensors”, published in IEEE Photonics Journal, volume 5, number 4, in August 2013, i.e. by recalibration on a centered circle of the ellipse obtained by Clarke transformation or equivalent of a multiphase system. It is again within the reach of the person skilled in the art to design an implementation thereof.But according to an advantageous and clever embodiment, these predetermined required conditions may comprise a predefined minimum number of sufficiently different phase shift values ​​produced by Clarke transformation or equivalent of the three-phase system of measurement signals S, for example according to a predefined model of distance between them and / or partitioning, to define and obtain a single ellipse solution by elliptical adjustment. In other words, if this minimum number is reached, then the elliptical adjustment is considered possible, reliable and of unique solution, so that the calculation of a dynamic operating characteristic value can be calculated and the calibration by elliptical adjustment and recalibration on a centered circle, the recording in memory 32 of the calibration parameters thus obtained, then the phase shift estimation can also be carried out on the basis of the multiphase system provided.

[0049] [Fig.2] illustrates different values ​​that can be used by the estimation device 12 of [Fig.l] to calculate at least one characteristic operating value of the interferometric system 10 from the three-phase system of measurement signals S supplied by the CCD sensor 26.

[0050] A first characteristic operating value is thus, for example, a static contrast value SC defined from extreme values ​​taken by the three-phase system of measurement signals S at a predetermined instant to. Preferably, this instant to corresponds to an exposure of the interaction branch 20 of the optical interferometer 14 to any predetermined reference environment, for example a stable reference environment without this being an obligation, in particular between 0 and 4 seconds or beyond 11 seconds in the non-limiting example of the time diagram of [Fig.2].

[0051] As a non-limiting example, the static contrast value SC can be defined as follows:

[0052] sc= i^ <rs * •_________' tsis.\ *• 1_________! my* ( P ( <o ) ) +™ n ( P ( k ) ) ’ htsN x * / isüN i /

[0053] where N=3 in the example of [Fig.2].

[0054] More precisely, etmin(p,(t0) ) = P3(t0) in the example of figure 2, from which çr, _ p2(t())-p3(k) P,(io)+P3(to) in this particular case. It should be noted that Pi(to) can correspond to the value taken by the measurement of the amplitude of the i-th optical signal of the multiphase system precisely at the instant to, or alternatively to the value taken by the measurement of an average of the amplitude of the i-th optical signal of the multiphase system around the instant to. The variant makes it possible to compensate for noisy micro-variations of the signals p;, present even in a stable environment.

[0055] A second characteristic operating value is for example a dynamic contrast value DCi defined for each i-th optical signal of the multiphase system from extreme values ​​taken by the measurement of this i-th optical signal of the multiphase system during a predetermined duration D, that is to say by the signal pi of the three-phase system of measurement signals S. Preferably, the measurement is taken while the interaction branch 20 of the optical interferometer 14 is exposed to an unstable interaction environment and is subjected to a condition of sufficient variation of the optical signals of the multiphase system, in particular between 4 and 10 seconds in the non-limiting example of the time diagram of [Fig.2].

[0056] As a non-limiting example, the dynamic contrast DC value for each i-th optical signal of the multiphase system can be defined as follows:

[0057] V i, Ei <N,DCi = kx max(p(f))-min(p(t) teD ■ 1 ' teD ' 1

[0058] where N=3 in the example of [Fig.2]. The coefficient of proportionality k can for example be equal to Uz.

[0059] According to the references in [Fig.2], for k = Uz, this gives the following system of equations:

[0060] । DC( = [Max(pJ-Min^)] / 2 • DC2=[Max(p2)-Min(p2)] / 2 IDC3 = [Max(p3) - Min(pJ] / 2

[0061] A third characteristic operating value is for example a dynamic offset value DOide defined for each i-th optical signal of the multiphase system from extreme values ​​taken by the measurement of this i-th optical signal of the multiphase system during the predetermined duration D, that is to say by the pi signal of the three-phase system of measurement signals S. Also preferably, the measurement is taken while the interaction branch 20 of the optical interferometer 14 is exposed to an unstable interaction environment and is subjected to a condition of sufficient variation of the optical signals of the multiphase system, in particular between 4 and 10 seconds in the non-limiting example of the time diagram of [Fig.2].

[0062] As a non-limiting example, the dynamic offset value DO; for each i-th optical signal of the multiphase system can be defined as follows:

[0063] yj 1

[0064] where N=3 in the example of [Fig.2]. The coefficient of proportionality k can for example be equal to ^2.

[0065] According to the references in [Fig.2], for k = / 2, this gives the following system of equations:

[0066] , Dqi = [ Max ( pi ) + Min(pi)] / 2 • ​IDO2 = [Max (p?) + Mm(p2)] / 2 IDO3 = [Max (p3) + Min(pj] / 2

[0067] According to the instructions of the computer program 34, the processing unit 30 is capable of determining an operating state of the interferometry system 10, from the calculated operating characteristic values, for example those defined previously, and from predefined reference values.

[0068] [Fig.3] illustrates a first non-limiting example of determining a state of operation of the interferometry system 10 from the static contrast value SC defined previously. In this example, two reference static contrast values ​​are recorded in memory 32. They can be defined by learning on several reference interferometry systems whose operating states are known. Given that the static contrast value SC is calculated globally on all the measured signals p;, 1 < i < N, it makes it possible to globally detect a malfunction of the interferometry system 10, that is to say to determine an undifferentiated operating state of the interaction branch 20 of its optical interferometer 14 or of at least one of the N outputs of the multimodal coupler 24, without actually being able to locate it in the interaction branch 20 or at the output of the multimodal coupler 24.But it can also, despite everything, be interpreted as characteristic of an operating state of the interaction branch 20 of the optical interferometer 14, more precisely of its interaction device 22. It can thus be considered that the weaker it is, the more the interaction device 22 is damaged, in particular by pollution. Thus, a first value . reference threshold SCrefi, for example set at 0.07, distinguishes a first state El, of interaction device 22 considered as unpolluted for any value SC > SCrefi, from a second state E2, of interaction device 22 considered as slightly polluted for any value SC < SCrefi. A second reference threshold value SCref2, for example set at 0.03, distinguishes the second state E2, of interaction device 22 considered as slightly polluted for any value SC > SCref2 (knowing further that SC < SCrefi), from a third state E3, of interaction device 22 considered as polluted for any value SC < SCref2.

[0069] In the example of [Fig.3] also, the interaction device 22 of the interaction branch 20 takes the form of a winding of optical fiber in contact with an external environment likely to damage it by pollution.

[0070] The one illustrated on the left side, noted 22A, is visibly in good condition. It consequently presents a three-phase system of measurement signals S with very little noise in which the measured signals p;, 1 < i < N, are very distinctive, so that the calculated static contrast value SC is approximately 0.16, that is to say greater than or equal to SCrefi. The interaction device 22A is therefore considered in the unpolluted state El.

[0071] The one illustrated in the central part, noted 22B, is visibly in poorer condition, especially on its left. It consequently presents a three-phase system of measurement signals S which is a little noisy in which the measured signals p;, 1 < i < N, remain nevertheless distinctive, so that the calculated static contrast value SC is approximately 0.03, that is to say strictly less than SCrefi but greater than or equal to SCref2. The interaction device 22B is therefore considered in the slightly polluted state E2.

[0072] The one illustrated on the right side, noted 22C, is visibly in poor condition, especially on its left. It consequently presents a noisy three-phase system of measurement signals S in which the measured signals p;, 1 < i < N, are more difficult to distinguish, so that the calculated static contrast value SC is approximately 0.01, that is to say strictly less than SCref2. The interaction device 22C is therefore considered in the polluted state E3.

[0073] [Fig. 4] illustrates a second non-limiting example of determining an operating state of the interferometry system 10 from the dynamic contrast value DC defined previously for each i-th optical signal of the multiphase system. In this example, a first reference dynamic contrast value DCref is recorded in memory 32. It can be defined by learning on several reference interferometry systems whose operating states are known. Given that the dynamic contrast value DC; is calculated for each of the measured signals p;, 1 < i < N, it can be characteristic of an operating state of each of the N outputs of the multimodal coupler 24, or, if it is averaged over all of the measured signals p;, 1 < i < N, of the branch interaction 20 of the optical interferometer 14, more precisely of its interaction device 22. It can be considered that the lower it is, the more the interferometry system 10 is deteriorated, in particular by pollution. Thus, the first reference dynamic contrast value DCref, for example set at 1.25 in the example of [Fig.4], defines a threshold below which the interferometric system 10 is considered to be out of use (state E0). Other reference dynamic contrast values ​​could also be defined above this first reference to define boundaries between the aforementioned states E1, E2 and E3.

[0074] More precisely, in the graphical representation of [Fig.4], it is the average q of the values ​​DQ, 1 < i < N, of dynamic contrasts which is represented with their standard deviation o at different successive instants tb • • tl3 separated for example from each other by a few days. The evolution over time of these values ​​of average q and standard deviation o is followed. Alternatively, any statistical value representative of the values ​​DCi, 1 < i < N, other than the average could of course be used.

[0075] According to a first monitoring possibility, as long as q remains stable or increasing, that is to say as long as q(tk.i) - q(tk) < ôq, where ôq is a strictly positive predetermined threshold value of decrease between two consecutive values ​​of dynamic contrast averages, the interferometric system 10 is considered to be in good working order. This is the case between times ti and t4 of [Fig.4]. On the other hand, as soon as q(tk [) - q(tk) > ôq, which occurs from time t5 of [Fig.4], the interferometric system 10 is considered to be in degraded working order due to probable pollution of the interaction branch 20 of the optical interferometer 14 and / or of at least one of the N outputs of the multimodal coupler 24.

[0076] According to a second possibility of monitoring compatible with the first, from the moment when the interferometric system is considered to be in a degraded operating state, the standard deviation o is specifically monitored. If it increases, as is for example the case in [Fig.4] between the times t5 and tn, this means that the pollution affecting the interferometric system 10 is heterogeneous and local on at least one of the N outputs of the multimodal coupler 24. If on the contrary it remains stable, this means that the pollution affecting the interferometric system 10 is homogeneous and global, probably at the level of the interaction branch 20 of the optical interferometer 14.

[0077] According to a third possibility of monitoring compatible with the first two, assuming that the interaction branch 20 of the optical interferometer 14 is always subjected to the same environment to be tested according to a constant measurement frequency, from the moment when the interferometry system 10 is considered to be in a degraded operating state, the average q is specifically monitored and experience shows that it generally follows approximately a straight line with a negative slope. It is then relevant to carry out a linear regression on the successively calculated values ​​of q, in this case the values ​​q(t5) to q(tn) to deduce values ​​a and [3, with a < 0, such that the equation q(t) = [3 + at is as close as possible to these values. We can then simply deduce a remaining lifetime of the interferometry system 10 by considering that q(t) decreases until it reaches, at a time tL, the threshold value DCref below which the interferometric system 10 is considered to be out of use (E0), i.e. DCref = [3+ atL or:

[0078] tL^ (DCref-(3) / a.

[0079] It is understood that other operating states or other estimates of the remaining lifetime of the interferometry system 10 can be determined from the aforementioned operating characteristic values, in particular also from the dynamic offset DO values, but also furthermore from other operating characteristic values ​​that can be defined and calculated from measurements of the multiphase system provided by the interferometry system 10.

[0080] Thus, for example, the static contrast value SC could also be monitored over time according to the monitoring principle of [Fig. 4]. It is of course not possible in this case to monitor the evolution of a standard deviation, since SC is a unique value at each instant for the interferometry system 10. The first and third monitoring possibilities mentioned above can then be applied, for global monitoring of malfunction or remaining life time of the interferometry system 10. But the second monitoring possibility mentioned above cannot be applied, which means that it is not possible to actually determine whether the malfunction is due to heterogeneous and local pollution or homogeneous and global pollution.

[0081] As for the dynamic shift value DO; defined previously for each i-th optical signal of the multiphase system, it can be monitored over time according to the principle of [Fig.4] and according to the same three monitoring possibilities mentioned above, for global and / or local monitoring of malfunction or remaining life time of the interferometry system 10.

[0082] The installation shown schematically in [Fig.5] comprises a shared plurality of interferometry systems such as that of [Fig.l] which bears the reference 10. The common elements taken from the installation of [Fig.l] bear the same reference.

[0083] Thus, this installation comprises a plurality of optical interferometers 14i... 14n which all receive the sinusoidal optical signal s0 generated and emitted by the laser source 16 and each provide two phase-shifted sinusoidal optical signals, denoted respectively Su, Si,2... sn,i, sn>2, to one of a plurality of respective multimodal couplers 24i... 24n, with n > 2. Each optical interferometer 14j, l <j<n, comporte avanta gently an interaction device which is specific to it in its optical interaction branch so that the n phase shifts obtained are respectively specific to the n optical interferometers 14i... 14n.

[0084] The n multimodal couplers 24,... 24n have two inputs, for receiving the n pairs of phase-shifted sinusoidal optical signals Si4, Si>2... sn4, sn>2, and three outputs for respectively supplying n three-phase systems of three sinusoidal signals s'^, s'l,2, S' 13... S'n>i, S'n>2, s'n3.

[0085] The n optical interferometers 14i... 14n form, respectively with the n multimodal couplers 24p.. 24n, n interferometry systems 10i... 10n.

[0086] In the case of the provision of optical three-phase systems, the n interferometry systems 10n share the same device 12 for estimating their operating state and therefore the same CCD photographic sensor 26 associated with the n multimodal couplers 24,... 24n which provide it with the n three-phase systems of three sinusoidal signals s'i l, s'i_2, s'i,3... s'n.i, s'n>2, s'n>3, for the provision of a set S of n electrical three-phase systems in each of which the three sinusoidal signals are phase-shifted by 2ir / 3. These 3n signals take the following form: P] j(t) =a1jcos[91(t)]+o14 ; P, 2(0 = a12COS[6,(t) +27T / 3]+O1t2 ; Pt3(t) =aMcos[0i(t)-27T / 3]+ob3; PILi(t); P^O) =an,2COS(0n(t) +2tt / 3] +0^2 ; P,^ (t) = an 3cos [0n (t) - 2rr / 3] + on-3.

[0087] The n interferometry systems 10i... 10n finally share the same computer system 28 specifically configured in the device 12 for estimating their operating state for processing the set S of the n three-phase systems provided in order to extract from them: - mainly one or more characteristic operating values, noted SC,, DCj,, DCj3, DCj„ DOji, DOj2, DOp, 1 < j < n, on [Fig.5] by analogy with the notations of [Fig.l], - incidentally an estimation of the n respective phase shifts between the pairs of phase-shifted sinusoidal optical signals Su, Si,2... sn.i, sn>2, as well as their respective evolutions over time, in the form of a set of n time signals SGj, 1 < j < n, for example made up of n sensorgrams in the context of fluid characterization.

[0088] The operation of the computer system 28 of [Fig.5] is unchanged from to what has been detailed with reference to [Fig.l], by means of a simple adaptation to simultaneously process the n three-phase systems provided instead of just one. This is the reason why it bears the same reference 28 and comprises the same processing unit 30 associated with the memory 32 in which the aforementioned processing means are recorded in the form of the software module or computer program 34 capable of being executed this time on the set S of the n three-phase systems provided.

[0089] The two preceding non-limiting examples of figures 3 and 4 for determining an operating state of the interferometry system 10 can therefore also be adapted simply to the shared installation of n interferometry systems 10i ... 10n of [Fig.5] by extrapolation so as to determine an overall operating state of the installation.

[0090] First of all, with regard to the example of [Fig.3], n static contrast values ​​SCj, 1 < j < n, for the n interferometry systems 10i... 10n can be calculated at a given instant and compared to the reference static contrast values ​​recorded in memory 32, to determine whether one or more interferometry system(s) 10i... 10n of the installation is malfunctioning.

[0091] As regards the example of [Fig.4], at each instant tk of the temporal monitoring a mean and a standard deviation of the n static contrast values ​​SCj, 1 < j < n, can be calculated, so that the three aforementioned monitoring possibilities can be applied. In this case, the possible localization of a malfunction thanks to the monitoring of the standard deviation is of course done at the scale of the installation and its different interferometry systems, not at the scale of the interferometry systems themselves and their internal functioning.

[0092] Still with regard to the example of [Fig.4], at each instant tk of the temporal monitoring an average (or any other representative statistical value) and a standard deviation of the nN dynamic contrast values ​​DCji, 1 < j < n, 1 < i < N, can be calculated, so that the three aforementioned monitoring possibilities can be applied. According to a non-limiting calculation possibility, the calculated average M(tk) is an average of the averages p,j(tk), while the calculated standard deviation S(tk) is the standard deviation of the averages qj(tk). In this case, the possible localization of a malfunction thanks to the monitoring of the standard deviation is of course done at the scale of the installation and its different interferometry systems, not at the scale of the interferometry systems themselves and their internal operation.On the other hand, once a malfunction is detected as heterogeneous and local, it can be localized and detected as homogeneous or heterogeneous within each malfunctioning interferometry system, according to the same reasoning as indicated previously, using the values ​​qj(tk) and Oj(tk).

[0093] The extrapolation of the previous paragraph also applies to the nN dynamic shift values ​​DOji, 1 < j < n, 1 < i < N.

[0094] The operation of the installation of [Fig.l], or the equivalent operation of the installation of [Fig.5], will now be detailed in a general manner with reference to [Fig.6].

[0095] During a prior interferometry step 100, the sinusoidal optical signal s0 generated and emitted by the laser source 16 passes through the optical interferometer 14 or the plurality of optical interferometers 14^.. 14n., for the provision of the two phase-shifted sinusoidal optical signals sb s2 or the 2n phase-shifted sinusoidal optical signals two by two s1>b s1>2... sn>b sn>2.

[0096] During a following acquisition step 102, these signals sb s2 or s1>b Si>2... sn>bsn 2 undergo multimodal coupling, possibly combined with CCD capture, to obtain the three-phase system S of three sinusoidal signals phase-shifted from each other by 2ir / 3 (or more generally a multi-phase system of N signals phase-shifted from each other by T / N where N > 2) or the set S of n three-phase systems in each of which the three sinusoidal signals are phase-shifted from each other by 2ir / 3 (or more generally n multi-phase systems in each of which the N signals are phase-shifted from each other by T / N where N >2).

[0097] During a subsequent recording step 104, the three-phase system S or the set S of n three-phase systems is at least partly recorded in memory 32. According to a first possible variant 104A, it is the entirety of the time signals which is recorded for the entire acquisition duration. According to a second possible variant 104B, only certain characteristic values ​​are extracted from the three-phase system S or from the set S of n three-phase systems and are then recorded: for example the extreme values ​​of [Fig.2].

[0098] During a following stop step 106, the acquisition of the three-phase system S or of the set S of n three-phase systems is stopped.

[0099] During a following test step 108, the processing unit 30 executes the computer program 34 to test whether the condition of sufficient variation of the signals of the three-phase system S or of the set S of n three-phase systems is met. This condition has been detailed previously and will not be repeated here. It will simply be noted that step 108 may require processing of the three-phase system S or of the set S of n three-phase systems such as a Clarke transformation or equivalent in the case where the teaching of the Halir et al document is followed to then carry out the phase estimation.

[0100] If the sufficient variation condition is met at the end of this test 108, the method of [Fig.6] moves on to a first step 110 of a method for estimating an operating state of the interferometry system 10 or of the n interferometry systems 10i... 10n. This first step 110, carried out by executing the computer program 34, proceeds to the calculation of at least one characteristic operating value such as those defined previously, in particular: - the calculation of at least one static value such as the SC value or the SCj values ​​defined previously, and - the calculation of at least one dynamic value such as the values ​​DCb DC2, DC3, DOb DO2, DO3, or DCjb DCj2, DCp, DOjb DOp, DOp defined previously since the sufficient variation condition is met.

[0101] If the sufficient variation condition is not met at the end of the test 108, the method of [Fig.6] moves on to a first alternative step 112 of the method for estimating an operating state of the interferometry system 10 or of the n interferometry systems 10i... 10n. This first alternative step 112, carried out by executing the computer program 34, proceeds to the calculation of at least one characteristic operating value such as those defined previously but not requiring the sufficient variation condition to be met, that is to say: - the calculation of at least one static value such as the value SC or the values ​​SCj defined previously, and possibly - the calculation of at least one dynamic value, but not such as the values ​​DCb DC2, DC3, DOb DO2, DO3, or DCjb DCj2, DCj3, DOjb DOj2, DOp defined previously which require that the sufficient variation condition be met.

[0102] The calculation carried out in step 110 or 112 is done using the data recorded in memory 32 during step 104.

[0103] Following step 110 or 112, the method for estimating an operating state of the interferometry system 10 or of the n interferometry systems 10i... 10n proceeds to a second step 114 for determining an operating state of the interaction branch of the optical interferometer 14 or of each of the n optical interferometers 14i... 14n and / or of at least one of the N outputs of the multimodal coupler of the interferometry system 10 or of each of the n interferometry systems 10i... 10n, or even possibly of a remaining lifetime of the interferometry system 10 or of the n interferometry systems 10i... 10n, as a function of the characteristic operating value(s) calculated in step 110 or 112, of their possible evolution over time, and of at least one predefined reference value, for example as explained and illustrated previously with reference to figures 3 and 4.

[0104] Finally, during a possible last step 116 of phase shift estimation: - an estimation of the phase shift between the phase-shifted sinusoidal optical signals Si, s2, as well as its evolution over time, in the form of a time signal SG, for example of the sensorgram type in the context of fluid characterization, or - an estimate of the n respective phase shifts between the pairs of signals phase-shifted sinusoidal optical signals Si>b Si>2... sn>b sn>2, as well as their respective evolutions over time, in the form of a set of n time signals SGj, l <j<n, par exemple constitué de n sensorgrammes en contexte de caractérisation de fluide, can be performed by executing the computer program 34.

[0105] The shared plurality of interferometry systems 10i... 10n of [Fig. 5] can be implemented in an electronic device 50 for olfactory characterization of a fluid such as that shown schematically in [Fig. 7]. This is a non-limiting example of a fluid characterization device according to a possible embodiment of the present invention for a non-limiting olfactory application of odor identification. It comprises a measuring chamber 52 intended to receive a fluid, for example a gas such as ambient air. To do this, it comprises a suction device 54 designed to suck in the air located inside the measuring chamber 52 and cause it to exit to the outside.It further comprises an air inlet 56 which can be selectively closed to keep the ambient air in the measuring chamber 52 or open to allow the evacuation of the ambient air from the measuring chamber 52 and its renewal by activating the suction device 54. It is thus provided with means for controlling the incoming and outgoing flows.

[0106] In its measuring chamber 52, the electronic olfactory characterization device 50 comprises several sensors, in particular olfactory sensors 58, distributed respectively over as many reactive sites, for example around sixty, designed to interact with compounds likely to be present in the measuring chamber 52 when the device 50 is placed near a fluid to be analyzed emitting these compounds, in particular when the air inlet 56 is near the fluid considered. The compounds emitted are generally volatile organic compounds but the present invention is not limited to such compounds.

[0107] Each olfactory sensor 58 is itself, for example, a biosensor designed to interact with the compounds of a particular family of volatile organic compounds. In practice, each olfactory sensor 58 may comprise a molecule, such as a peptide immobilized on a substrate or a polymer covering a surface, complementary to the compounds of the family associated with this olfactory sensor 58. The general idea is to functionalize reactive sites using olfactory sensors 58 (i.e. biosensors, polymers, carbon nanotubes, etc.) such that they adsorb and desorb the volatile organic compounds in a differentiated manner, to form a differentiated molecular interaction response of the olfactory sensors, and to amplify the response in the form of a sequence S of electrical measurement signals using a physical transduction device.

[0108] Alternatively, the electronic olfactory characterization device 50 could be suitable for being brought into contact with any other fluid, liquid or gaseous, than ambient air. It could also, according to a particularly simple version, not include the suction device 54 and the air inlet 56, or even the measuring chamber 52. In this simple version, the olfactory sensors 58 are then capable of being directly brought into contact with the fluid to be analyzed without flow control.

[0109] The olfactory sensors 58 are associated with a transducer 60 with which they interact. This transducer 60 is arranged and configured to measure any change in physical property caused by an interaction of the olfactory sensors 18 with the fluid to be analyzed. It provides the electrical measurement signal S which is presented for example in the form of a sequence of electrical measurement signals and characterizes this fluid since this sequence is representative of the volatile organic compounds with which the olfactory sensors 58 can interact in the measurement chamber 52.

[0110] More precisely, the transducer 60 is a system for processing by interferometry a periodic signal, i.e. the periodic signal s0 previously defined and supplied to the plurality of interferometry systems 10i... 10n. It comprises more precisely the plurality of optical interferometers 14i... 14n which all receive the periodic signal s0 and each have one of the sensors 58 as an interaction device of their interaction branch. There are therefore as many optical interferometers 14i... 14n in the transducer 60 as there are sensors 58.

[0111] As a non-limiting example, the transducer 60 is, as mentioned previously, a system for amplifying optical index variation by Mach-Zehnder interferometry, for example according to a Mach-Zehnder interferometer matrix technology, called MZI technology (from the English “Mach-Zehnder Interferometer”), and even more precisely a multimodal interference MZI technology, called MZI / MMI technology (from the English “Multi Mode Interference”), since the transducer 60 further comprises the n multimodal couplers 24i... 24n with two inputs, for receiving the n pairs of input signals Si4, Si>2... sn4, sn>2, and with three outputs for the respective supply of n three-phase systems of three sinusoidal signals s'i l, s'i.2, s'i>3... s'n>i, s'n>2, s'n>3, as well as the CCD 26 photographic sensor shared to provide the set S of the n three-phase systems as an electrical measurement signal.This transducer 60 is therefore configured to measure any change in a refractive index due to an interaction of the fluid studied with at least any one of the olfactory sensors 58 thanks to the detectable phase shift between the reference branch and the interaction branch of the optical interferometer on which this any olfactory sensor is arranged.

[0112] The electronic olfactory characterization device 50 further comprises several functional modules which will be described below. In the example described, these modules are of a software nature. Thus, the device 50 comprises the system in computer system 28 previously described, the latter comprising the processing unit 30 and the associated memory 32 in which several computer programs or several functions of the same computer program are recorded, including in particular the software module or computer program 34. These computer programs comprise instructions designed to be executed by the processing unit 30 in order to carry out the functions of the software modules. They are presented as distinct, but this distinction is purely functional. They could just as well be grouped according to all possible combinations in one or more software programs. Their functions could also be at least partly micro-programmed or micro-wired in dedicated integrated circuits, such as digital circuits.Thus, as a variant, the computer system 28 could be replaced by an electronic device composed solely of digital circuits (without a computer program) for carrying out the same functions. Also as a variant, at least some of the aforementioned computer programs could be remote and accessible by the computer system 28 via the Internet. Generally speaking, even if all of the aforementioned software and memory components are presented as being gathered in the same computer system 28, they could just as easily be dispersed in separate hardware elements, or even distant from each other, but interconnected in a network (data transmission bus, local network, wide area network, Internet, etc.).

[0113] The electronic olfactory characterization device 50 thus firstly comprises a software module 62, intended to be executed by the processing unit 30, for controlling the suction device 54 (if it is provided in the device 50), the air inlet 56 (if it is also provided in the device 50) and the transducer 60.

[0114] It further comprises, optionally but advantageously, a software module 64, intended to be executed by the processing unit 30, for selecting, from among the olfactory sensors 58 of the electronic olfactory characterization device 50, a subset of sensors sensitive to volatile components characteristic of a desired olfactory imprint. These characteristic volatile components may vary from one application or fluid studied to another so that the selection of olfactory sensors carried out by the software module 64 may also vary and be parameterized. The selected subset comprises, for example, M > 1 olfactory sensor(s), in particular advantageously several olfactory sensors (M > 2).

[0115] The electronic olfactory characterization device 50 further comprises the software module or computer program 34, already defined and described in detail, intended to be executed by the processing unit 30, for: - extract M sensorgrams SG j, js{L .... M} respectively representative of the interactions of the M selected olfactory sensors with the volatile organic compounds concerned from the values ​​specific to these M olfactory sensors in the sequence S of three-phase systems provided by the transducer 60, and - calculate one or more characteristic operating values ​​such as those mentioned previously from the sequence S of three-phase systems provided by the transducer 60 to determine an operating state of the interaction branch of each optical interferometer 14i ... 14n and / or of at least one of the N outputs of each multimodal coupler 24 i... 24n, as well as a possible remaining lifetime.

[0116] Figure 8A thus illustrates the superimposed time diagrams of around sixty sensorgrams SGj, je {1, ..., M} obtained over a period of approximately 190 seconds according to a well-controlled measurement protocol, involving control of the suction device 54 and the air inlet 56, in which: - the olfactory sensors 58 are first exposed to a reference fluidic environment with a carrier fluid without the presence of the target compounds of a fluid to be analyzed during a first reference state identifiable by a first PHI portion of the sensorgrams, - they are then exposed to the fluid to be analyzed during a second analytical adsorption state triggered by a controlled injection of this fluid into the measuring chamber 52, this second state being identifiable by a second portion PH2 of the sensorgrams, and - they are finally exposed again to the reference fluidic environment during a third final state of desorption by a controlled evacuation of the fluid to be analyzed from the measuring chamber 52, this third state being identifiable by a third portion PH3 of the sensorgrams.

[0117] It is in particular during the first reference state that the static operating characteristic values ​​can be calculated and during the second analytical adsorption state that the dynamic operating characteristic values ​​can be calculated.

[0118] Returning to Figure 7, the electronic olfactory characterization device 50 further comprises an optional software module 66, intended to be executed by the processing unit 30, to carry out possible prior processing on the M sensorgrams SGj, je {1, ..., M} provided by the software module 34.

[0119] This pre-processing comprises for example a low-pass filtering implemented in the form of a digital filter with finite or infinite impulse response. This involves filtering the high-frequency measurement noise in the raw signals as provided by the software module 34. A Butterworth filter with finite impulse response of the first order and cutoff frequency normalized to 0.45 (i.e. value of the ratio between the cutoff frequency and the sampling frequency equal to 0.45) is suitable.

[0120] This preliminary processing further comprises, for example, a calculation of a norm within the meaning of patent document WO 2020 / 141281 A1 on the M sensorgrams SGj, je{l, M] filtered or not to obtain M filtered and / or normalized sensorgrams SG- j E { 1, ..., M} •

[0121] The electronic olfactory characterization device 50 further comprises a software module 68, intended to be executed by the processing unit 30, to obtain in a well-known and non-detailed manner a characterization or SIG signature of the composition of the fluid to be analyzed from the M sensorgrams SGj, j G { 1, ..., M} or SGj, j E { 1, . M] • This characterization or SIG signature can take the form of a standardized olfactory signature as illustrated in [Fig.8B] in the form of a circular diagram. It will be noted that this module can proceed in two stages: firstly the obtaining of a first intermediate signature, then the transformation of this first intermediate signature by normalization.

[0122] The SIG signature illustrated in [Fig.8B] comprises sixty-four components. The software module 68 can therefore optionally but advantageously be further programmed to transform the SIG signature, whether standardized or not, into another simplified SIG' signature by component reduction. A method using linear discriminant analysis LDA (from the English "Linear Discriminant Analysis"), principal component analysis PCA (from the English "Principal Component Analysis"), independent component analysis ICA (from the English "Independent Component Analysis"), autoencoder, etc., is suitable. For a SIG signature with sixty-four components such as that of [Fig.8B], a simplified SIG' signature with two or three components can be obtained.

[0123] A method of olfactory characterization of a fluid corresponding to the execution of software modules 34 and 62 to 68 will now be detailed in accordance with the succession of steps in [Fig.9].

[0124] During a first optional step 200 carried out by executing the software module 64, a portion of the olfactory sensors 58 is selected based on a desired olfactory imprint.

[0125] During a following step 202, the electronic olfactory characterization device 50 is brought close to a fluid so as to obtain an interaction of the fluid with each of the selected olfactory sensors 58. On this occasion, the software module 62 is executed.

[0126] During a following step 204, the transducer 60 provides a sequence S of measurement signals in interaction with the olfactory sensors 58.

[0127] During a following step 206 carried out by executing the software module 34, the processing unit 30 provides the M sensorgrams SGj, j G {1, ..., M} representative of an interaction of the fluid with each olfactory sensor 58 selected after having carried out a blind calibration and an estimation of phase shifts. During this same step, it can provide, in accordance with the general principles of the present invention, the determination of an operating state of the interaction branch of each optical interferometer 14P.. 14n and / or of at least one of the N outputs of each multimodal coupler 24i... 24n.

[0128] During a following optional step 208 carried out by executing the software module 66, the processing unit 30 provides the M sensorgrams SG'j, je (1, M}.

[0129] Finally, during a last step 210 carried out by executing the software module 68, the processing unit 30 provides the signature SIG or SIG' from the M sensorgrams SGj, je {1, ..., M} or SG'j, je ( 1, ..., M}.

[0130] It is clear that a device for estimating an operating state of one or more interferometry systems such as one of those described previously with reference to FIGS. 1 and 5 makes it possible to improve the monitoring of the operation of this or these interferometry systems by making it both simpler and at least as effective. This results in better anticipation of any malfunction likely to alter the measurements. Such a device also finds a particularly advantageous application in the characterization of a fluid by the use of an electronic device such as that illustrated in [Fig.7].

[0131] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them. In the detailed presentation of the invention which is given above, the terms used should not be interpreted as limiting the invention to the embodiments set out in the present description, but should be interpreted to include all equivalents whose prediction is within the reach of those skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Claims

1. Method for estimating an operating state of an interferometry system (10; 10p.. 10n) comprising an optical interferometer (14; 14i... 14n) with a reference branch (18) and an interaction branch (20), for providing two separate optical signals (sb s2 ; Si.ps[j2 • • • sn,b sn>2) from the same periodic optical signal (s0) of period T, combined with a multimodal coupler (24; 24p.. 24n) with N>2 outputs, capable of providing a multiphase system of N optical signals (s'p s'2, s'3 ; s'i.p s'i,2, s'1,3... s'n>i, s'n>2, s'n>3) formed to be phase-shifted from each other in the period T from of the two separate optical signals (sb s2 ; s 1>b s1>2...sn,u sn>2), characterized in that it comprises: - a calculation (110, 112) of at least one characteristic operating value (SC, DCi, DC2, DC3, DOi, DO2, DO3) defined from at least one measurement (S) of the multiphase system; and - as a function of this at least one characteristic operating value (SC, DCi, DC2, DC3, DOi, DO2, DO3) and of at least one predefined reference value, the determination (114) of an operating state (E0, El, E2, E3) of the interaction branch (20) of the optical interferometer (14; 14i ... 14n) and / or of at least one of the N outputs of the multimodal coupler (24; 24p.. 24n).

2. Method for estimating an operating state of an interferometry system (10; 10p.. 10n) according to claim 1, further comprising an estimation (114) of the remaining lifetime (tL) of the interferometry system (10; 10p.. 10n) as a function of a change over time of at least one of said at least one characteristic operating value (SC, DCp DC2, DC3, DOp DO2, DO3).

3. Method for estimating an operating state of an interferometry system (10; 10p.. 10n) according to claim 1 or 2, wherein the calculation (110, 112) of said at least one characteristic operating value (SC, DCp DC2, DC3, DOp DO2, DO3) comprises: - the calculation (110, 112) of at least one static value (SC) defined from values ​​(pi(t0), p2(t0), p3(t0)) taken by said at least one measurement (S) of the multiphase system at a predetermined instant (t0); and - the calculation (110) of at least one dynamic value (DCi, DC2, DC3, DOi, DO2, DO3) defined from values ​​(Min(pO, Max(pO, Min(p2), Max(p2), Min(p3), Max(p3)) taken by said at least one measurement (S) of the multiphase system during a predetermined duration (D) subject to a condition of sufficient variation of the optical signals of the multiphase system, this calculation being carried out only if this condition of sufficient variation is actually fulfilled.

4. A method for estimating an operating state of an interferometry system (10; 10i... 10n) according to claim 3, wherein the sufficient variation condition comprises the fact that each optical signal of the multiphase system results from enough different phase shift values ​​so that they cover at least the period T.

5. Method for estimating an operating state of an interferometry system (10; 10i... 10n) according to any one of claims 1 to 4, wherein said at least one operating characteristic value (SC, DCi, DC2, DC3, DOi, DO2, DO3) comprises a static contrast value SC defined from extreme values ​​taken by said at least one measurement (S) of the multiphase system at a predetermined instant, for example: - at an instant to where the interaction branch (20) of the optical interferometer (14; 14i... 14n) is exposed to a reference environment; and - according to the definition max(p.(t0) )-min(p (t(.) j , where n ( is 1 ' ' * Is&Nv 1 \ \ U / J+^sCpXk)) ) ] <tsN ' 1 7 ; { ■ la mesure de l’amplitude du i-ème signal optique du système multiphasé à l’instant to ou la mesure d’une moyenne de l’amplitude du i-ème signal optique du système multiphasé autour de l’instant to.

6. Method for estimating an operating state of an interferometry system (10; 10i... 10n) according to claim 5, in which: - at least one reference static contrast value is predefined, in particular by learning on several reference interferometry systems whose operating states- tion of interaction branches are known; the static contrast SC value is compared with this at least one reference static contrast value to determine whether the interaction branch (20) of the optical interferometer (14; 14i... 14n) is in good working order or not.

7.

8. Method for estimating the operating state of a system interferometry (10; 10i... 10n) according to any one of claims 1 to 6, wherein said at least one characteristic operating value (SC, DCi, DC2, DC3, DOi, DO2, DO3) comprises a dynamic contrast value DQ defined for each i-th optical signal of the multiphase system from extreme values ​​taken by said at least one measurement (S) of this i-th optical signal of the multiphase system during a predetermined duration D, for example: for a duration D, where the interaction branch (20) of the optical interferometer (14; 14i... 14n) is exposed to an unstable interaction environment, subject to a condition of sufficient variation of the optical signals of the multiphase system; and according to the definition qq = kx max ( p. ( t ) ) - min ( p. ( t ) ) ] 1 teD VC 7 ! teD VC ' / j , where k is a proportionality factor, for example 0.5, and p.(t) is the measure of the amplitude of the i-th optical signal of the multiphase system at time t. Method for estimating an operating state of an interferometry system (10; 10i... 10n) according to any one of claims 1 to 7, wherein said at least one characteristic value of operation (SC, DCi, DC2, DC3, DOi, DO2, DO3) comprises a dynamic offset value DOj defined for each i-th optical signal of the multiphase system from extreme values ​​taken by said at least one measurement (S) of this i-th optical signal of the multiphase system during a predetermined duration D, for example: for a duration D, where the interaction branch (20) of the optical interferometer (14; 14i... 14n) is exposed to an envi- unstable interaction mode, subject to a condition of sufficient variation of the optical signals of the multiphase system; and - according to the definition DO: - kx [max( p.( t) ) +min( p.(t ) ) ' where ^ is a proportionality factor, for example 0.5, and p. (t ) is the measure of the amplitude of the i-th optical signal of the multiphase system at time t.

9. Method for estimating an operating state of an installation with a shared plurality of interferometry systems (10i... 10n) each comprising an optical interferometer (14i... 14n) with a reference branch (18) and an interaction branch (20), for providing two separate optical signals (su, Si,2... sn.i, sn>2) from the same periodic optical signal (s0) of period T, combined with a multimodal coupler (24i..• 24n) with N>2 outputs, capable of providing a multiphase system of N optical signals (s'i l, s'i_2, s'i,3... s'n.i, s'n>2, s'n>3) formed to be phase-shifted from each other in the period T from the two separate optical signals (si4, Si,2... sn>b sn>2), this installation being intended in particular to be integrated into an electronic fluid characterization device, the method comprising the execution of the steps of a method according to any one of claims 1 to 8 for each of its interferometry systems (10i...10n) so as to extrapolate the determination of an overall operating state of the installation.

10. Computer program (34) downloadable from a communication network and / or recorded on a medium (32) readable by a computer (28) and / or executable by a processor (30), comprising instructions for executing the steps of a method for estimating an operating state of an interferometry system (10; 10i... 10n) according to any one of claims 1 to 8 or of an installation with a shared plurality of interferometry systems (10i... 10n) according to claim 9, when said program (34) is executed on a computer (28).

11. Device (12) for estimating an operating state of at least one interferometry system (10; 10i... 10n), each interferometry system (10; 10i... 10n) comprising an optical interferometer (14; 14i... 14n) with reference branch (18) and interaction branch (20), for providing two separate optical signals (sb s2 ; s1>b s1>2 • • • sn,b sn>2) from the same periodic optical signal (s0) of period T, combined with a multimodal coupler (24; 24b.. 24n) with N>2 outputs, capable of providing a multiphase system of N optical signals (s'b s'2, s'3 ; s'^, s'i,2, s'i,3... s'n>i, s'n>2, s'n>3) formed to be phase-shifted from each other in the period T from the two separate optical signals (sb s2 ; s1>b Si>2... sn,u sn>2), the estimation device (12) comprising: - an optical sensor (26) of the N outputs of each multimodal coupler (24; 24i... 24n) to obtain measurement signals from each multiphase system; - a unit (30) for processing the measurement signals; characterized in that the unit (30) for processing the measurement signals is configured (34) to: - extract at least one measurement (S) of each multiphase system from the measurement signals and calculate at least one characteristic operating value (SC, DCb DC2, DC3, DOi, DO2, DO3) defined from this at least one measurement (S); and - depending on this at least one characteristic operating value (SC, DCb DC2, DC3, DOb DO2, DO3) and at least one predefined reference value, determining an operating state (E0, El, E2, E3) of the interaction branch (20) of the optical interferometer (14; 14b.. 14n) and / or at least one of the N outputs of the multimodal coupler (24; 24b.. 24n) of each interferometry system (10; 10i ... 10n).

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